Dana's confirmation of darwin's theory 495 



The most curious thing to note about Dana's argument is the manner 

 in which it has been neglected or discredited, not only by Darwin, but by 

 Semper, Eein, Murray, Guppy, Agassiz, Gardiner, and a host of others. 

 Crosby, Penck, and Langenbeck are among the few who recognized the 

 testimony of embayed shorelines in favor of Darwin's theory previous to 

 1900 ; its strength has been more generally perceived since then, but there 

 are still many students of the old problem who overlook it; yet what can 

 be clearer than this testimony when the attention is once directed to it! 

 The facts have long been known. Tahaa, drawn in figure 1 as seen look- 

 ing north from a summit on its neighbor, Eaiatea, in the northwestern 

 part of the Society group, justifies the account given over 80 years ago 

 by two missionaries, who said that it is distinguished by "the number, 

 breadth, and commodiousness of its harbors, with which the v^hole coast 

 is indented, some running quite into the heart of the country." One of 

 the harbors is sketched in figure 2, looking northwest from a point marked 

 X in figure 1 ; the highest summit of the island, 1,936 feet in altitude, is 

 indicated by three dots in both figures. Eaiatea was instanced 75 years 

 ago by Darwin as possessing "those deep arms of the sea . . . which 

 penetrate nearly to the heart of some [reef-] encircled islands" (49). Its 

 embayments were originally much larger than now, as is shown by the 

 strong line drawn in figure 3 back of the present shoreline, according to 

 my records of a two-day trip around the lagoon, to mark the junction of 

 valley-sides with (white) delta flats. A similar rnap of Tahaa is given in 

 one of my earlier articles (1916, c, 488). Numerous other islands have 

 correspondingly embayed shorelines and have long been known to have 

 them, and the correct interpretation of embayed shorelines v^as, as above 

 noted, clearly stated by Dana nearly 70 years ago ; yet these manifest facts 

 and their manifest interpretation, of so critical importance in the coral- 

 reef problem, have been ignored by most writers on the subject until 

 recent years. This curious aspect of the coral-reef problem has been set 

 forth in an earlier article (1913) published on the centenary of Dana's 

 birth. 



EMBAYED SHORELINES AND THE GLACIAL-CONTROL THEORY 



It is not only because embayed coasts demand unlike periods of time 

 for their erosion and unlike amounts of submergence for their embayment 

 that they can not be explained by changes of ocean level, such as are 

 postulated in the Glacial-control theory. The absence of partly sub- 

 merged cliffs on inter-embayment spur ends that are fronted by fringing 

 or close-set barrier reefs also contradicts an essential consequence of that 

 theory; for the theory assumes that while the ocean was lowered and 



